example-of-function-based-mixin-composition-with-class-and-shared-local-state.js

// example-of-function-based-mixin-composition-with-class-and-shared-local-state.js

function withExposableSharedLocalState (state) {
    state = ((typeof state === "object") && state) || (void 0);

    var json_stringify  = JSON.stringify;
    var json_parse      = JSON.parse;

    var compositeType   = this;

    compositeType.valueOf = function () {
        return ((typeof state !== "undefined") ? json_parse(json_stringify(state)) : state);
    };
    compositeType.toString = function () {
        return json_stringify(state);
    };
    return compositeType;
}

const withEnumerableFirstLast = (function withEnumerableFirstLastFactory () {
    function first () {
        return this[0];
    }
    function last () {
        return this[this.length - 1];
    }
    return function withEnumerableFirstLast () {
        const enumerableType = this;

        enumerableType.first = first;
        enumerableType.last = last;

        return enumerableType;
    };
}());

function withEnumerableListProxy (sharedList) {
    sharedList = withEnumerableFirstLast.call((Array.isArray(sharedList) && sharedList) || []);

    const compositeType = this;

    compositeType.first = function () {
        return sharedList.first();
    };
    compositeType.last = function () {
        return sharedList.last();
    };
    return compositeType;
}

class Queue {
    constructor () {
        const
            queue = this,
            list  = [];

        queue.enqueue = function (item) {
            list.push(item);
            return item;
        };
        queue.dequeue = function () {
            return list.shift();
        };
        withEnumerableListProxy.call(queue, list);
        withExposableSharedLocalState.call(queue, list);

        return queue;
    }
}

const queue = new Queue();

queue.enqueue("the");
queue.enqueue("quick");
queue.enqueue("brown");

console.log("queue : ", queue);

console.log("queue.enqueue('fox') : ", queue.enqueue('fox'));
console.log("queue.first() : ", queue.first());
console.log("queue.last() : ", queue.last());

console.log("queue.dequeue() : ", queue.dequeue());
console.log("queue.first() : ", queue.first());
console.log("queue.last() : ", queue.last());

console.log("queue.valueOf() : ", queue.valueOf());
console.log("queue.toString() : ", queue.toString());
console.log("('' + queue) : ", ('' + queue));